Effect of Milnacipran on Pain Processing and Functional Magnetic Resonance Imaging (fMRI) Activation Patterns in Patients With Fibromyalgia

Experimental: 1

Twice daily oral administration of milnacipran for 5 weeks, placebo for 2 weeks, and crossover to placebo for 5 weeks.

Droga: Milnacipran

Twice daily oral administration of Milnacipran for 5 weeks.

Droga: Placebo

Twice daily oral administration of placebo for 5 weeks.

Experimental: 2

Twice daily oral administration of placebo for 5 weeks, placebo for 2 weeks, and crossover to milnacipran for 5 weeks.

Droga: Milnacipran

Twice daily oral administration of Milnacipran for 5 weeks.

Droga: Placebo

Twice daily oral administration of placebo for 5 weeks.

Change in Medium Pressure Pain Threshold From Baseline to End of Treatment.

Pain intensity is rated using the Gracely Box Scale, where 0 is no pain sensation and 20 is extremely intense. Painful blunt pressure is applied to the thumbnail of the patient's left hand. A software system will determine medium(rated as 7 or 8) and high pain (rated as 13 or 14) thresholds at baseline, week 5 and at a second baseline at week 7 and week 12.

Change in Diffuse Noxious Inhibitory Control (DNIC) Effect From Baseline to End of Treatment.

DNIC is evaluated using a conditioning stimulus and a test stimulus. Painful blunt pressure is applied to the thumbnail of the patient's left hand for 30 sec. Patient rates pain experienced on numerical scale of 0(no pain) to 100(worst pain) at 10, 20 & 30 sec. This is repeated 3 times and a mean pain score is calculated. 5 minutes following test stimulus, patient's right hand is immersed in 12C water at 30 sec test stimulus is reapplied and a 2nd mean pain score is calculated. The difference in mean pain rating before and after conditioning stimulus indicates presence and magnitude of DNIC